Background:The emergence and spread of plasmid-mediated quinolone resistance (PMQR) among extended-spectrum betalactamase (ESBL)-producing isolates have become a serious threat to global public health. Objectives:The purpose of this study was to determine the presence of PMQR determinants in ESBL-producing Klebsiella pneumoniae isolates from hospitalized patients. Methods: We collected 100 strains of K. pneumoniae from patients admitted to Milad Hospital. Antimicrobial susceptibility and ESBL production were tested based on the Clinical and Laboratory Standards Institute (CLSI) guidelines. Polymerase chain reaction (PCR) was used to determine the presence of ESBL and PMQR genes. The genetic relatedness among the strains was evaluated by enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR). Results: We found 51% (n = 51) of the isolates as ESBL producers. Among them, the highest resistance rates were to cefepime (76.5%), amikacin (74.5%), ciprofloxacin and levofloxacin (both 70.6%), and the lowest resistance rate was to ticarcillin (96%). Among the 51 ESBL-positive isolates, blaTEM (94.1%) was the most frequent gene, followed by blaSHV (66.7%) and blaCTXM (59.9%). The frequencies of aac(6')-Ib, qnrS, qnrD, qnrB, qnrA, and qnrC were 35.3%, 33.3%, 31.4%, 29.4%, 13.7%, and 5.9%, respectively. Coexistence of ESBL and PMQR genes was observed in 44 (86.2%) isolates. ERIC-PCR analysis revealed that ESBL producers were genetically divergent. Conclusions: Our findings indicate that PMQR genes are highly prevalent in ESBL-producing strains of K. pneumoniae in Iran. Regular detection of ESBL strains and monitoring of their antibiotic resistance patterns may help reduce the spread of these strains in hospitals.